Is it better for your body to run in the morning or at night?

Some mornings you roll out of bed and tackling a treadmill run feels like an uphill battle—even at a zero percent incline. Other days, you’ve got nothing left in the tank to log post-work, nighttime miles. Whether you call yourself an a.m. workout warrior or are more of a sunset sweater, there are certainly benefits to squeezing in strides at both times of day. But is one particularly better than the other? Well, that depends on what your goals are.

When you first wake up in the morning, your body isn’t exactly primed and prepared for activity. When you’re rolling out of bed, you’ve been inactive for upward of six hours. This means that most of your body functions are less than ideal (body temperature, flexibility, mobility). Not to mention your energy stores are depleted, so that your body doesn’t have much to pull from in terms of fuel.

“This is the reason for the high perceived rate of exertion and respiration when running in the morning,” says Brad Whitley, DPT at Bespoke Treatments in Seattle. “If you choose to run in the morning, you might incur a physiological speed bump due to the low body temperature, leading to a longer warm up period.”

The good news? A longer warm up period could pay off big time. You can utilize your endorphin rush (AKA the runner’s high) to begin your day on a high note and carry it into the work day. Plus, there are other science-backed benefits of getting your workout on as the sun rises. Running in the morning is more effective at lowering blood pressure and inducing better sleep—as opposed to any other time of day—according to one study published in Vascular Health and Risk Management. Brigham Young University researchers also found that a morning workout could curb appetite as the day progresses, setting you up to resist the inevitable sugar crash that hits at 3 p.m.

When it comes to night miles, that low body temperature, lack of flexibility are irrelevant. The hardest thing at this point, per Whitley, could just be finding the motivation when you’d rather be couch-side. So what’s a lady to do? Take two things into consideration: First, are you training for a race coming up, or pounding the pavement for fun? If you’ve got a race on deck, Whitley suggests getting after it at a time similar to the race start, which in all likelihood means that training in the morning could actually work in your favor.

“Your body’s natural circadian rhythm can adapt to perform better at certain times of the day,” he says. “Running or working out at the time when your race is an easy and predictable way to prepare your body for performing its best on race day.” Secondly, what time of day do you enjoy working out? This is ultimately the biggest factor in what will impact a steady, constant exercise routine. Remember: this is supposed to be enjoyable, no matter what time of day you hit the ground running.